How long would it take to die if hypothermia?

Depends: If you are dry, naked on an ice floe, you are much safer than wet or immersed in water because the heat loss is so much faster in the water.....It is best to avoid hypothermia and death.

Hartd to say: There have been many times that a "dead" person has been brought to the er only to have them be revived through warming and life support. There is a saying that "they are not dead until they are warm and dead". There are documented cases where that motto has been forgotten and the patient wakes up in the morgue!